I did the exact same operation on the server but the two devices are different. On the USB version I have to enter a pin on the device when the server application tries to communicate with the device. Thats not necessary on the R232 version. Other than that, I did the same read operation.

Is there anything I can do to give you a log out of Ubuntu mate/rdesktop? I always thought both use the same rdp protocol - so it's confusing to me why it works with Ubuntu and not with WTware.

Would it make any difference the specify the device path to /dev/ttyUSB0 ? Thats how I successfully redirect the r232 version using rdesktop.

I set up an old Widows XP machine with RS232 port to monitor both the original (RS232) and RS232 to USB connection. I add them as attachment. I had to shorten the log due to personal informations.
Thanks.

I reinstalled Ubuntu MATE and wasn't able to redirect my smartcard reader. Then I realized i had to give the ttyUSB device permissions-

sudo chmod go+rw /dev/ttyUSB0

After that, it worked without problems.

Any chance this is related to the problem WTware has?

Readme:

The installation requires root access rights.

If medCompact terminal devices will be connected via RS232 to the system, the
administrator shall enable write access to the corresponding devices (e.g.
/dev/ttyS0 for COM1). Regarding COM1 this can be done using the command:

sudo chmod go+rw /dev/ttyS0

This command asks for the root password.

Supported distributions
This tool has been tested successfully on SuSE 10.3 and Ubuntu 8.4 ("hardy heron").